Voltage-controlled electron multiplier



31, 1940- K. S'CHLESINGER 2,221,022

VOLTAGE-CONTROLLED ELECTRON MULTIPLIER Filed Oct. 5, 1937 lnyentor:

Patented Dec. 31, 1940 PATENT", OFFICE VOLTAGE-CONTROLLED ELEbTRON MULTIPLIER Kurt Schlesinger, Berlin, Germany, assignor, by

mesne assignments, to Loewe Radio, Inc., a corporation of New York Application October 5, 1937, Serial No. 167,346

In Germany October 9, 1936 Claims.

The electron multiplier owes its superiority to the previous photo-cell amplifiers inthe amplification of weak light intensities to the fact, as well known, that the primary current is 5 subjected to full-range control between brightness and darkness. As in the case of black the current is zero there is no basic noise? caused by the shot effect.

The introduction into this multiplier of a control electrode or grid has not been successful heretofore owing to the shot effect of the feed .current in the first stage, which is modulated only to a very inadequate extent by the grid which is introduced. The signal potentials at the first grid are much too weak to control the primary feed current down to zero. If on the other hand the primary current is weakened to such a degree as to render control down to zero possible, the efliciency of the first system becomes undesirably small.

The utilisation of the multiplier for amplifying voltages demands that the feed currents of the first system is zero when the signal voltage is zero.

The solution of this problem is accomplished by the use of a high quality cathode ray or Braun tube with a very fine image point, the cathode ray of which is, e. g. by means of plate deflection, deflected by the signal to a greater or smaller extent through a fine-perforated diaphragm.

In the stationary condition the ray is disposed to the side of the diaphragm aperture.

In the co-pending patent application Ser. No. 167,380, filed 10th of October 1937 adischarge tube has been described and claimed, in which the electrons to be multiplied are controlled in quantity by at least one deflection field generator, more particularly a deflecting condenser. The present invention represents an additional development of a tube of this character and provides certain additional aspects in respectof its practical embodiment.

In the following description of the invention reference will be made to the appended drawing, thesingle figure of which shows, in diagrammatical sectional elevation, a tube according to the invention with the essential circuit elements associated therewith.

In the figure the cathode ray system is represented by the cathode l, the tubular member 2 and the anode 3. The anode 3 is preferably operated at ground potential, as is one of the deflecting plates 4a, while the second deflecting plate 4 has the potential to be amplified im- 5 pressed thereon from a source which is conven- ,1 an electron image of the very small opening or aperture which is located at 6 at the tubular 5 member to act as an object diaphragm and which is of the order of .1 mm. in diameter. The diaphragm l is provided with an aperture which is also small in diameter. By means of an auxiliary magnet or a slight biassing of the plate 4 in relation to the plate to the image point is projected to the side of the aperture. Upon the application of the signalling potential 5 the electrons enter the multiplier through the aperture in the diaphragm l to a greater or smaller ex- 5 tent commencing at zero. The multiplier is shownin the drawing in its known embodiment asjelectro-magnetic multiplier wherein a homogeneous magnetic field should be imagined to be disposed vertical to the plane of the paper.

The electrons which pass through the aperture in diaphragm 1 impinge upon the electrode elements 9 and 9" in sequence as is known in the art and are then, collected by a collector electrode I0 which is connected to supply the input signal to an amplifier H or other load.

For the functioning of the arrangement there are essential:

1. Large deflection sensitivity of the cathode my system in millimetres per volt,

2. The size of image point comparable with the deflection amplitude, which means a very fine image point.

For these reasons the anode potential 8 will be kept as low as possible and the plates 4, 4a will be made long and narrow and the free length of the beam, i. e. the distance between 3 and I as long as possible.

of transit of the electrons comes within the order of the wave period. If micro-waves are to be amplified it will accordingly preferably be attempted to attain the required sensitivity by reducing the distance between the plates, and not by increasing their lengths.

I claim:

1. An arrangement for amplifying varying voltages comprising an electron discharge tube, means within the tube for producing an electron beam, an apertured diaphragm, means for focussing said electron beam completely upon impermeable parts of said diaphragm, deflecting means adapted to be energized by said varying voltages for causing said electron beam to pass through the aperture of said diaphragm to Varying de grees dependent upon the magnitude of the varying voltages and an electron multiplying system adapted to multiply the number of electrons passing through said aperture of said diaphragm.

2. An arrangement for amplifying varying voltages comprising an electron discharge tube, means for producing an electron beam within said tube, an apertured diaphragm, means for focussing said electron beam completely upon impermeable parts of said diaphragm, deflecting means adapted to be energized by said varying voltages for causing said electron beam to pass to a varying degree through the aperture of said diaphragm and an electron multiplying system comprising a series of electrodes activated for secondary electron emission for multiplying the number of electrons passing through said aperture of said diaphragm and a terminal anode for collecting the electrons.

3. An arrangement for amplifying varying voltages comprising an electron discharge tube, means for producing an electron beam within the tube, an apertured diaphragm, means for focussing said electron beam in the plane of said diaphragm, an electron beam deflecting system,

meansfor supplying said deflecting system with a constant energization of such an amount that said electron beam is completely directed upon impermeable parts of said diaphragm, means for superposing to said constant energization a varying energization produced by said varying voltages for causing said electron beam to pass to a varying degree through the aperture of said diaphragm and an electron multiplying system adapted to multiply the number of electrons passing through said aperture of said diaphragm.

4. An arrangement for amplifying varying voltages comprising an electron discharge tube, means for producing an electron beam within said tube, an apertured diaphragm, means for focussing said electron beam in the plane of said diaphragm, an electron beam deflecting means for causing a constant deflection .of said electron beam of such an amount that said electron beam is completely directed upon impermeable parts of said diaphragm, a second deflecting means adapted to be energized by said varying voltages for causing said electron beam to pass to a varying degree through the aperture of said diaphragm and an electron multiplying system adapted to multiply the number of electrons passing through said aperture of said diaphragm.

5. An arrangement for amplifying varying voltages comprising an electron discharge tube, means for producing an electron beam within the tube, an apertured diaphragm, means for focussing said electron beam completely upon impermeable parts of said diaphragm, electron beam deflecting means adapted to be energized by said varying. voltages for causing a varying deflection of said electron beam of such an amount of said electron beam in its most deflected state completely passes through said aperture of said diaphragm and an electron multiplying system adapted to multiply the number of electrons passing through said aperture of said diaphragm.

6. An arrangement for amplifying varying voltages comprising an electron discharge tube, means for producing an electron beam within the tube, an apertured diaphragm, means for focussing said electron beam completely upon impermeable parts of said diaphragm, a pair of electron beam deflecting plates, means for energizing at least one of said plates by said varying voltages for causing said electron beam to pass to a varying degree through the aperture of said diaphragm and an electron multiplying system adapted to multiply the number of electrons passing through said aperture of said diaphragm, said deflecting plates having a length which is smaller than the length for which the transit period of the electrons is equal to the wave period. '7. An arrangement for amplifying varying voltages comprising an electron discharge tube, means for producing an electron beam within the tube, an apertured diaphragm, means for focussing said electron beam completely upon impermeable parts of said diaphragm, a pair of deflecting plates adapted to be energized by said varying voltages for causing said electron beam to Pass to a varying degree through the aperture of said diaphragm and an electron multiplying system adapted to multiply the number of electrons passing through said aperture of said diaphragm, said deflecting plates having a length which is smaller than the length for which the transit period of the electrons is equal to the wave period and being so arranged with respect to one another that said electron beam in its most deflected state completely passes through said aperture.

8. An arrangement for amplifying varying voltages comprising an electron discharge tube, means for producing an electron beam within the tube, an apertured diaphragm, means for focussing said electron beam completely upon impermeable parts of said diaphragm, apair of deflecting plates adapted to be energized by said varying voltages for causing said electron beam to pass to a varying degree through the aperture of said diaphragm and an electron multiplying system adapted to multiply the number of electrons passing through said aperture of said diaphragm, said deflecting plates having a length which is smaller than the length for which the transit period of the electrons is equal to the wave period and being so arranged with respect to one another that the peak value 'of said varying voltage just causes said electron beam to pass completely through said aperture.

9. An arrangement for amplifying varying voltages comprising an electron discharge tube having included therein means for developing an electron beam, an apertured diaphragm positioned within the tube, means for focussing the developed electron beam normally upon electron impermeable parts of the diaphragm, electron beam deflecting means adapted to be energized by the varying voltages to be amplified for causing the electron beam to pass through the aperture of the diaphragm to varying degrees, dependent upon the magnitude of the varying voltages and an electron multiplying system for multiplying the electrons passing through the said aperture of the diaphragm and an electron collector means for collecting the multiplied electrons and a load circuit to receive the collected electrons.

10. An arrangement for amplifying varying voltages comprising an electron discharge tube having included therein means for producing a centered electron beam and for directing the beam longitudinally of the tube, a diaphragm element having an aperture therein located substantally along the longitudinal axis of the tube, a plurality of electron beam deflecting means positioned intermediate the electron beam developing means and the said diaphragm, means for applying to one of the beam deflecting means biasing energy 'for normally directing the electron beam upon an electron impermeable por-,

tion of the diaphragm, means for applying the varying voltages to be amplified to the other of said plurality of beam deflecting means for causing the developed electron beam to pass through the aperture of the diaphragm to varying degrees proportionally to the magnitude of the varying voltages and an electron multiplying system for multiplying the electrons passing through the aperture of the diaphragm and a load circuit for utilizing the multiplied electrons.

KURT SCHLESINGER. 

